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PubMed1983

Recent advances in our understanding of pentastomid reproductive biology.

Pentastomids are arthropod parasites which attain maturity in the respiratory tracts of vertebrates. All pentastomids exhibit an obvious sexual dimorphism in that fully mature females are invariably much bigger than males. Unusually though, copulation, which happens only once in the lifetime of females, occurs when both sexes are approximately the same size and the uterus of the female is undeveloped. This is because sperm is stored in spermathecae which, being positioned at the junction of the oviduct and uterus, become more remote from the vagina as the uterus elongates during development. The provision of spermathecae for sperm storage allows oocytes, shed continuously from the ovary, to be fertilized from time to time. What renders this process quite remarkable, and possibly unique, is the extreme length of the patent period. In one species this can extend up to an estimated 10 years and is associated with an egg production of about 10(6) eggs/female/year. Spermathecal structure provides some clues as to how prolonged sperm storage and the continuous fertilization of oocytes is accomplished. The upper region of the access duct is a narrow, chitinized tube which tapers to as little as 3 microns diameter at the point of entry into the spermatheca. The chitinous (?) lining of the spermatheca is relatively impermeable and apparently functions to totally isolate sperm from external influences: stored sperm are arranged in bundles and whorls and remain totally quiescent and inactive during the storage period. The entire spermatheca is invested by muscle fibres, the contraction of which will express small numbers of sperms through the narrow access duct. These are then reactivated by secretions from the female reproductive tract: the extreme narrowness of the spermathecal duct provides the fine adjustment of the system. The narrowness of the duct also creates problems during the process of insemination, since sperm discharged directly into the female reproductive tract would be unlikely to find the spermatheca through such a structure. Accordingly, the male cirrus is much modified to directly penetrate the spermathecal duct during copulation. Sperms, stored in the male seminal vesicle, are apparently activated prior to sperm transfer, and swim along the cirrus to be guided directly into the spermathecal lumen. Some unusual variations on the normal pentastomid life-cycle are discussed.

Animals↗
PubMed2001

Identification and synthesis of a male-produced sex pheromone from the stink bug Chlorochroa sayi.

The reproductive behavior of the stink bug Chlorochroa sayi was studied in the laboratory. There was a sexual maturation period of about 10 days before bugs began mating. Sexually mature adult bugs engaged in courtship consisting of antennation and head-butting of the female by the male, before the female adopted a receptive posture and copulation occurred. Both sexes mated multiple times during their life-spans, with the mean duration of copulations of virgin bugs (42.3 +/- 19.6 min) and experienced bugs (37.3 +/- 28.4 min) being similar. Most matings were initiated in the late afternoon or evening, when pheromone production by males was greatest. Males transferred sperm and nutrients constituting about 17% of their body weight to females during mating. Three male-specific components, methyl geranate, methyl citronellate, and methyl (E)-6-2,3-dihydrofarnesoate in a ratio of 100:0.45:1.6, were first detected in volatiles collected from male bugs on green beans about 9-12 days after the final molt to the adult stage. In vertical Y-tube bioassays, females were attracted to odors from mature male bugs, and to a blend of the three male-produced components. Low numbers of females also were attracted in field trials with the three-component blend. The relatively weak attraction may be a result of other, as yet unknown cues being required in addition to the pheromone, such as visual or substrate-borne vibrational cues.

Animals↗
PubMed1988

Medial amygdaloid lesions and the regulation of sociosexual behavioral patterns across the estrous cycle in female golden hamsters.

Two experiments were conducted to examine the behavioral effects of medial amygdaloid (M) lesions during the estrous cycle in female golden hamsters. In Experiment 1, males were paired with gonadally intact M-lesioned, sham-operated, or ovariectomized M-lesioned females and tested in large enclosures. Medial amygdaloid lesions reduced, significantly, the occurrence of precopulatory biting attack and vaginal scent-marking behavior in females. In contrast, M lesions produced a significant increase in the duration of copulation. Mating behavior was also observed for a brief period of time in 1 M-lesioned female during the diestrus period and in 2 ovariectomized animals. After copulation, M-lesioned females attacked their mating partner less frequently than did sham-lesioned animals, which suggests that M lesions may modulate the reduction of both pre- and postcopulatory aggressive behavior by common processes. The attenuation in aggressive responsiveness was further documented in Experiment 2, which shows that during intrasexual fights, M-lesioned females exhibited significantly fewer offensive agonistic responses than did sham-operated opponents. Collectively, the results demonstrate that M lesions produce significant alterations in both social and sexual response patterns and suggest that M may be a neural component of a forebrain inhibitory system regulating the display of feminine copulatory behavior.

Amygdala↗
PubMed2000

Relation of Fos-IR expression in the pelvic ganglion to sexual behavior in laboratory rats.

The pelvic ganglion (PG) provides both sympathetic and parasympathetic innervation to the genitalia and other pelvic structures. To determine whether neuronal activity; of the PG, as detected by Fos-like immunoreactivity (Fos-IR), is related to sexual stimulation, male and female rats were tested under a variety of conditions. In males, Fos-IR expression in the PG was positively correlated with the amount of both genital and noncontact stimulation. In females, only ejaculation preceded by multiple intromissions induced a significant increase in Fos-IR; multiple intromissions or ejaculation preceded by only 0-1 intromission did not affect Fos-IR. Additional experiments comparing Fos-IR expression, in which some females were allowed to pace their sexual contact and others were not, revealed that ejaculation duration was the key factor in the induction of Fos-IR in female rats. Because the conditions under which Fos-IR expression occurred in females are identical to those required for sperm transport, we suggest that, in the female, sperm transport is regulated in part by autonomic outflow from the PG after copulation. These relations between sexual behavior and measures of PG activity are consistent with the idea that the sexually dimorphic organization of the peripheral nervous system plays a major role in mediating the gender-specific outcome of copulation: ejaculation in the male and sperm transport in the female.

Animals↗
PubMed1988

Sexual activity and satiety over an extended observation period in prairie voles (Microtus ochrogaster).

This study was designed to delineate the course of sexual satiation in prairie voles (Microtus ochrogaster). Fourteen male-female pairs were allowed to copulate freely for 24 hr under continuous observation. Copulations occurred predominantly during the first few hours and decreased in frequency thereafter. The mean number of ejaculations per pair was 5.6 (range, 2-9). Two thirds of the ejaculations occurred during the first 3 hr, and over 90% took place within the first 7 hr after the first intromission. No ejaculations were observed during the last 8 hr. These results suggest that male capacity to deliver ejaculations to a female is limited and that direct observations reveal a more limited capacity than observations made with time-lapse videotape.

Animals↗
PubMed1990

An unusual pattern of copulatory behavior in a South American cricetid rodent: Akodon molinae.

We describe the copulatory behavior and the morphology of the male genital tract of a member of a tribe (Akodontini) for which no information on copulatory behavior has been available. Copulation in Akodon molinae is characterized by multiple intromissions with no intravaginal thrusting, a single ejaculation, and a brief lock with the deposit of a plug. This pattern is unusual because of the combination of locking with both multiple intromissions and plugs. The latter combination, and similar standard measures of copulatory behavior, have been reported for Acomys cahirinus, a murid that frequently shows more than 1 ejaculation. Also, the standard measures of copulation in A. molinae resemble those of Calomys callosus, another South American cricetid, which shows intravaginal thrusting and infrequent locks. The functional significance and the anatomical correlates of locking and plug deposition in this species are discussed.

Animals↗
PubMed1997

Differences in the sexual conditioned behavior of male and female Japanese quail (Coturnix japonica).

The conditioned responses of male and female Japanese quail (Coturnix japonica) were compared in a Pavlovian conditioning procedure in which presentation of a brief conditioned stimulus was immediately followed by the release of a copulation partner. Male quail vigorously approached the conditioned stimulus and were much more likely to enter the compartment housing their copulation partner than were female birds (Experiment 1). In females, sexual conditioning resulted in increased squatting (Experiment 2). This response was the reflection of sexual behavior rather than more general social behavior (Experiment 3). These findings provide the first definitive evidence of sexual learning in female quail and are consistent with the interpretation that sexual conditioning increases sexual arousal or receptivity in both sexes but the increase has different behavioral manifestations in male and female quail.

Animals↗
PubMed2006

Effects of enclosure size on sexual behavior of Japanese quail (Coturnix japonica).

The authors determined whether results of experiments on copulatory and affiliative behavior of pairs of Japanese quail (Coturnix japonica) conducted in a closely confining apparatus would predict behavior in a large enclosure in which female quail could avoid contact with male quail. As found previously in studies of closely confined quail, in a large enclosure containing numerous barriers, both unmated female quail and mated female quail laying unfertilized eggs were more likely to remain near a confined male quail than were mated female quail laying fertilized eggs. Furthermore, the number of copulations that a pair engaged in when closely confined predicted the number of copulations that they engaged in when they were in the large enclosure. Patterns of affiliation and of mating in a confining laboratory apparatus thus predicted behavior in a larger enclosure that provided female quail with opportunity to avoid contact with male quail.

Animals↗
PubMed2004

The discriminative stimulus effects of cocaine in a pavlovian sexual approach paradigm in male Japanese quail.

Two groups of male Japanese quail (Coturnix japonica) were trained [corrected] to discriminate cocaine from saline in a conditioned approach procedure maintained by sexual reinforcement. For 1 group, cocaine (10 mg/kg ip) was administered prior to a conditioned stimulus (CS) that predicted copulation; saline followed by a CS predicted no copulation. A second group underwent the opposite training regimen. Results revealed apparent between-group differences in the rates of acquisition of the discrimination; however, during extinction trials, both groups responded more under the drug condition that predicted the female than to the condition that predicted no female. The results suggested that a drug discrimination may be maintained by sexual reinforcement. The findings are discussed with regard to interactions of cocaine and sexual reward, as well as to Pavlovian conditional stimulus control.

Animals↗
PubMed1976

A copulatory system in the hypothalamus and tegmentum of the domestic chick.

A tract in the chick is described that runs from the posterior nucleus paraventricularis magnocellularis (PVM) through the lateral hypothalamus to a small area of the anterior tegmentum, which is adjacent to the ventral tegmental area. Bilateral lesions of the posterior PVM or of the PVM tract or of its tegmental destination abolish the facilitation of copulation in male chicks by testosterone. The effect is specific in that the facilitation of attack is either unaffected or only slightly depressed by such lesions, while being itself specifically depressed by other hypothalamic lesions. No other hypothalamic tracts were found that were necessary for the facilitation of copulation. An equivalent copulatory system probably exists in the mammal, with a more diffuse distribution in the preoptic area but with similar connections back to the tegmentum.

Aggression↗
PubMed2004

Sperm death and dumping in Drosophila.

Mating with more than one male is the norm for females of many species. In addition to generating competition between the ejaculates of different males, multiple mating may allow females to bias sperm use. In Drosophila melanogaster, the last male to inseminate a female sires approximately 80% of subsequent progeny. Both sperm displacement, where resident sperm are removed from storage by the incoming ejaculate of the copulating male, and sperm incapacitation, where incoming seminal fluids supposedly interfere with resident sperm, have been implicated in this pattern of sperm use. But the idea of incapacitation is problematic because there are no known mechanisms by which an individual could damage rival sperm and not their own. Females also influence the process of sperm use, but exactly how is unclear. Here we show that seminal fluids do not kill rival sperm and that any 'incapacitation' is probably due to sperm ageing during sperm storage. We also show that females release stored sperm from the reproductive tract (sperm dumping) after copulation with a second male and that this requires neither incoming sperm nor seminal fluids. Instead, males may cause stored sperm to be dumped or females may differentially eject sperm from the previous mating.

Animals↗
PubMed2003

Extra-cellular dopamine increases in the paraventricular nucleus of male rats during sexual activity.

Dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) concentrations were measured in the dialysate obtained with vertical microdialysis probes implanted into the paraventricular nucleus of the hypothalamus of sexually potent male rats. Animals showed noncontact erections when put in the presence of, and copulated with a receptive (ovarietomized oestrogen and progesterone primed) female rat. Dopamine and DOPAC concentrations in the paraventricular dialysate increased 140% and 19%, respectively, above baseline values during exposure to the receptive female and 280% and 31%, respectively, during copulation. No changes in dopamine and DOPAC concentrations were detected in the paraventricular dialysate when sexually potent male rats were exposed to nonreceptive (ovariectomized not oestrogen plus progesterone primed) female rats. These results confirm the involvement of the paraventricular nucleus in control of erectile function and copulatory behaviour and show for the first time that dopamine neurotransmission is increased in this hypothalamic nucleus when erection occurs in physiological contexts.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1976

Courtship in Drosophila mosaics: sex-specific foci for sequential action patterns.

Mosaic fate mapping is used to locate the foci determining sex-specific steps in the mating behavior of Drosophila. Male performance of following females and displaying wing vibration toward them requires that a focus inside the head be constituted of male tissue, regardless of the sex of the head sense organs, the legs, the wings, or the thoracic ganglion. For attempted copulation to occur, a second focus in the thoracic region must also be male. Courtship by males is induced by a posteriorly located focus in the female, but an anterior female focus determines receptivity to attempted copulation. The interplay of male and female foci in the complex behavioral sequence is delineated.

Animals↗
PubMed1982

Esterase 6 in Drosophila melanogaster: reproductive function of active and null males at low temperature.

Esterase 6 is a polymorphic carboxylesterase (carboxylic-ester hydrolase, EC 3.1.1.1) localized to the reproductive tract of male Drosophila melanogaster and transferred to females at copulation. The reproductive fitness of males is strongly affected by temperature and the esterase 6 alleles (active versus null) that they carry. Low temperature (18 degrees C) dramatically changes the character of reproductive functions relative to optimal 25 degrees C. Males with active esterase 6 mate sooner, copulate for a shorter time, and produce more progeny per mating than do esterase 6 null males at 18 degrees C, in contrast to equal progeny production at 25 degrees C. A male esterase 6 effect on the remating speed of females at 25 degrees C is absent at 18 degrees C. Previous work suggests that male esterase 6 promotes ejaculate transfer, sperm storage, and use in females. The differences in reproductive fitness at 18 degrees C noted here may follow from the effects of esterase 6 on sperm transfer and utilization. The esterase 6 effect on productivity is consistent for different female types, even though the components of productivity that were affected, egg laying and egg fertility, changed with female type. These data lead to the hypothesis that the wide-spread polymorphism for esterase 6 may be adaptively significant.

Animals↗
PubMed1998

Effect of age and multiple mating on the mating behavior of Culicoides nubeculosus (Diptera: Ceratopogonidae).

The mating behavior of the biting midge Culicoides nubeculosus (Meigen) may be divided into a number of stages, including resistance behavior of the female before copulation. A previous study indicated that resistance behavior is a method through which the female assesses the fitness of the male, allowing some degree of mate choice. Our study used behavioral and electrophysiological techniques to investigate whether insect age and the reproductive status of the females influenced mating behavior. Virgin females became increasingly receptive to mating attempts as they aged, with reduced resistive behavior and a reduction in the time required for genital union. With increasing male age, the duration of copulation increased, possibly related to the time required for the transfer of sperm. Previously mated females were very resistant to further attempts to mate by males. Secondary matings were achieved only through the persistent efforts of males, although when successful, there were no differences in the duration of the mating process from matings with virgin females. Virgin female C. nubeculosus release a volatile sex pheromone which is detected by the males' antennae. Electrophysiological recordings from male antennae indicated that mated females have a continued but reduced output of this pheromone, which may allow males to distinguish virgin from mated females. The findings of the study are discussed in relation to possible methods of mate choice in this species.

Age Factors↗
PubMed1988

A novel postcopulatory block of reproduction in white-footed mice.

Female white-footed mice (Peromyscus leucopus) fail to produce offspring when paired with a male from weaning until 150 days of age if an adult female or her odor is also present. The present study delineates more clearly which stage of the young female's reproductive cycle is inhibited by the chemosignal of the older female. Age at vaginal opening and first estrus are delayed by the presence of the older female, but only for about 10 days. The presence of a male counteracts this delay. Thus, the basis for the block is not a delay in puberty. The older female's presence does not influence the number of estrous cycles experienced during the 30 days following first estrus, nor does it influence the number of corpora lutea found at autopsy. The presence of sperm in the vaginae of young females indicates that they were copulating. Likewise, examination of embryos 2 and 3 days after copulation reveals normal developmental progress. However, implantation does not occur in young females that have been exposed to an adult female. Thus, the block occurs either during the final stages of embryo transport or in relation to the implantation process itself.

Animals↗
PubMed1995

Male phenotype and ejaculate quality in the zebra finch Taeniopygia guttata.

We tested the idea that female preference for relatively attractive extra-pair males arises because the morphological and behavioural features that females find attractive covary with ejaculate features: Sheldon's (Proc. R. Soc. Lond. B 257 25-30 (1994) phenotype-linked fertility insurance hypothesis. Two phenotypic traits that female zebra finches find attractive in males are song rate and symmetry of chest band plumage, but we found neither of these to be significantly related to any of the following ejaculate features: number of sperm, percentage of live sperm, absolute number of sperm, sperm length or sperm swimming velocity. Furthermore, and surprisingly, we did not find the predicted negative relationship between male song rate and fluctuating asymmetry of chest band plumage. Because most ejaculate features (except sperm numbers in rested males) show low levels of repeatability, it is unlikely that female zebra finches could reliably obtain a better quality ejaculate by choosing to copulate with a more attractive male. There was thus no evidence for the phenotype-linked fertility insurance hypothesis. Nor did we obtain evidence for the more general fertility insurance hypothesis: we found that female zebra finches paired to a vasectomized male, and hence receiving no sperm, were no more likely to seek an extra-pair copulation than females paired to an intact male.

Animals↗
PubMed2000

Copulatory courtship and cryptic female choice in red flour beetles Tribolium castaneum.

Males of many animal species engage in courtship behaviours during and after copulation that appear to be solely aimed at stimulating the female. It has been suggested that these behaviours have evolved by cryptic female choice, whereby females are thought to impose biases on male postmating paternity success. Males of the red flour beetle Tribolium castaneum rub the lateral edges of the females' elytra with their tarsi during copulation. We manipulated female perception of this behaviour by tarsal ablation in males, thus preventing males from reaching the edge of the female elytra with their manipulated legs, and by subsequently performing a series of double-mating experiments where the copulatory behaviour was quantified. We found a positive relationship between the intensity of the copulatory courtship behaviour and relative fertilization success among unmanipulated males. This pattern, however, was absent in manipulated males, where female perception of male behaviour differed from that actually performed. Thus, female perception of male copulatory courtship behaviour, rather than male behaviour per se, apparently governs the fate of sperm competing over fertilizations within the female, showing that copulatory courtship is under selection by cryptic female choice.

Animals↗